Lubricating grease composition



Feb. 12, 1946. 1 w SPROULE ET AL 2,394,567

LUBRICATING GREASE COMPOSITION Filed Dec. 17, 1941 Y 2 sheets-sheet 1V OHoppa O/l..

($8 Y /7 TAN/ FHZIYOI. AND V /aLUM/NUMSOPS f 2 /3 HAAT/Nc.

KLTTl- /6 i Scuw SCRAPER emula 25 26 v 22 l V83 l JJ,

Feb. 12, 1946. I. W. SPROULL- ET AL 2,394,567

I LUBRICATING GREASE COMPOSITION Filed DBC. 17 1941 2 Sheets-Sheet` 2Hoppa. v l

Ollf TAN/4 w ,f

all. Til/KNER .3 oLUT/ON TANK 1 SCRLW CoNveYoR Pmsted Feb. 1.2,- 194e.

LUBaIcATrNG GnEAsEcoMrosmoN Lome w. spreuk, sansa, ontario, canada, and

John C. Zimmer, Union, N. J., assi Standard Oil Development Company, acorporation of Delaware Application December 17, 1941, Serial No. 423,27

' 14 claims. (c1. l25e- 37) This invention relates to aluminum soapgreases highly advantageous in the lubrication of machinery operatingunder conditionsof local high temperature increases, of irregular andshock load effects, and of frictional forces beyond the iilm strength'of any lubricating oil base material. 'Ihe invention relates more'particularly to aluminum soap greases adapted for-the lubrication ofindustrial machinery and the chassis parts of automobiles and crawlertype tractors and to an improvedprocess for the preparation of suchgreases.

Aluminum soap greases have proven to be outstanding lubricants for manytypes of industrial machinery and especially for the lubrication ofautomotive and tractor chassis parts. Difficulties, however, in th'emanufacture of aluminum soap greases have greatly hampered theirproduction and utilization. It is well known for example that whenaluminum stearate is dispersed in a mineral oil at an elevatedtemperature and the product cooled, compositions unsuitable aslubricants are obtained. The compositions, for example, vary in texturefrom being stringy, viscous liquids to solids having a hardfand grainystructure. However, when the so'ap dispersions are carefully cooled insmall quantities, a change in structure usually occurs and there isobtained a firm, transparent gel suitable as a lubricant. On themanufacturing scale attempts therefore to cool quickly bulk quantitiesof aluminum soap-oil blends have resulted in the formation of physicallyheterogeneous mixtures unsuitable for lubrication purposes. Eilectingthe rapid cooling in thin layers isunsatisfactory because often timesthere are formed soft granular masses unsuitable as grease typelubricants. Thus, on the commercial scale it has been found' necessaryto undertake the costly and laborious process of running th'e hot greasecomposites after blending into shallow pans then allowing the mass 'tocool equipment for reworking and then filtering to effect -the removalof any granular surface iilms and to obtain a relatively homogeneouscomposition.

pounds thus greatly expedites the manufacturev slowly, then passing themixture to suitable in structure may occur from being a viscous,

glitty liquid to that of being a suitable gel. This change, however,occurs only when the cooling period is between eight and sixteen hoursand when the mass is cooled in small quantities without agitation.However, in the process of cooling large quantities of grease a portionat the outer surface rapidly changes to a gel, while the'rest of themass hasnot attained the necessary temperature for the transition tosuitable gel formation.

Under these processing conditions the outer layers readily break downdue to excessive growth of soap particles, and thereafter form thin,liquid 1/4." thick-to temperatures as' low as' 50 F. without granulationor decomposition. The use in this manner of small quantities of phenoliccom cf aluminum soap greases; Furthermore, this use of phenoliccompounds permits the preparation f grease directly from the coolingdevices into larg'e shippingjcontainers, without reworking or filtering.

These advantageous eii'ects of phenolic compounds have been found tooccur without the developxnent of any disadvantageous eifects upon anyof the desirable lubricating properties of aluminum soap greases.Moreover, these advantageous effects of phenolic compounds in aluminumsoap greases'are not disadvantageously affected by the presence ofaccessory additive materials such as oil thickening agents,anti-corrosive and anti-oxidation agents.

Thus the present invention relates to the preparation of highlystabilized aluminum soap grease compositions containing a phenoliccompound as the special additive material for a grease mixture ofsuitable mineral oil base and an aluminum soap of a saturated fatty acidcontaining between 10 and 20 carbon atoms in the molecule, such asaluminum stearate. The amount in which the phenolic compound is presentin the compositions varies usually between 5% and 30% by weight of theamount of the aluminum soap. The aluminum soap is blended with th'emineral oil to form a grease of suitable composition in amounts between3% and 20% but usually between about I 3% and 10% by weight of the oil.Accessory constituents to impart to the composites other desirablecharacteristics include free, unsaturated fatty acids containing and 20carbon atoms in the molecule and their aluminum soaps, naphththenicacids and their aluminum soaps; and oil thickening agents, such as latexor polybutene.

Phenolic compounds in general havebeen found' f to be effective asadditives to grease compositions according to the present invention.vl{Initl'ie `choice oi a phenolic compound as a suitable blending agentfor a particular grease composition, selection is made largely on the*basic of its vapor pressure and its relative effects upon oilsolubility and misclbility with other-@'constituents as regardseffecting the lowering of-f the transition temperature. It is alsoimportant to select the phenolic compound on the basis of its efiect inphysically stabilizing the finished grease. Thus it has been found thatthe mono nuclear phenols are in general slightly more eiective than thepoly nuclear phenolic compounds, and that for vapor 'pressureandsolubility characteristics it until all of the soap and phenoliccompounds are thoroughly incorporated to form a smooth homogeneous mass.The mass after heating is then rapidly cooled by passing through coolingequipment to a temperature of about 90 F. The cooling may be effected bypassing the material into -shallow pans and then returning the coolgrease to mixing equipment wherein the mixture is allowed to settle toabout the transition tempera- -,ture.- Onv the otherlhand, the materialmay be plied the further quantities of oil as are required to preparethe. finished grease. The mixture is then passed through a coil heaterat a temperature of about 300 F. and then allowed is preferable toemploy the alkylated phenolic v compounds. In regard to the physicalstabilization of the grease products certain of the substituted phenolssuch 'as the amino phenols are preferable. However, substitutedphenolssuch as the halogenated and sulfur-bearing derivative are eflective.yParticularly effective phenols are the alkylated compounds having one ormore alkyl side chains. Of the various phenolic compounds effective forpurposes of this invention particular mention may be made of naturallyoccurring phenols, derived especially from petroleum and coal tar, thecresols, the amyl phenols, dihydric phenols, a-naphthol and -naphthol.

kThe effect of the vphenolic. compounds appears to be connectedpre-eminently with the compounding and cooling steps in the preparationof the greases. It appears that phenolic compounds function in thealuminum soap-mineral oil blends to permit rapid cooling withoutcrystallization of the aluminum soaps. Thus, the phenolicrv compoundspermit the mixture after to settle to permit the separation of anyoccluded gases before passing through a helical screw type cooler. Bythis means a grease can be satisfactorily prepared in large quantitieson a continuous basis, and the product directly passed to the shippingcontainers from the cooling equipment.

`An illustration of the methodr of preparing the grease involving theuse of the usual type kettle for heatingand blending the constituents iscompounding to be agitated during cooling and the transition instructure to occur at the' lower temperatures than hithertofore invessels of even 400 lbs. capacity. l 1

In preparing the lgrease compositions of this invention, the oilemployed is preferably derived from a naphthenic base crude, as forexample oils of the Coastal type. The viscosity of the oil is usuallyabove about 85 seconds Saybolt at 210 F., and preferably from to 200seconds Saybolt at 210 F. The aluminum soap and the phenolic compoundsare added to the oil at a temperature between about 130 F. and 150 F.The heating may be carried out in a coil type heater or in the usualtype kettle. A suitable heating kettle is furnished with mechanicalmeans .of agitation, usually paddles having at the outer sweeps closefitting scraper adjustments to pass over its inner surface in order toinsure good heat transfer and to obviate the development' of surfaceiilms. Usually the aluminum soap and the phenolic compounds are blendedwith about 10% to 20% of the total quantity of the oil to be used andthe mixtureworkedinto a thick non-lumpy paste. This paste is thenstirred into the balance of the oil, and heated to a temperature ofbetween 280 F. and 300 F. and held at that temperature ing uid in theJacket '2L ternally with paddles Il having scraper termi nals I2 whichcan be finely adjusted to work upon the entire surface of the kettle.The motion of the paddles in. the kettle insuresvery complete andthorough agitation within the kettle. The jacket portion i3 of thekettle I0 is adapted for the passing in through line I4 and the passingout through line' I5 of steam eitherl under normal or superatmospheric'pressure as temperatures within the kettle I0 require. Under theconditions of such means of agitation and of a temperature between about280 F. and about 300 F., suflcient oil of suitable character as amineral oi1 base for the preparation of the grease composition issupplied from storage tank I6 to the kettle I0 through line I1 andadmixed with the aluminum .soap and phenolic compoundsv supplied throughopening I8 to make a smooth thick paste. Further quantities of oil tomake the grease of desired consistency are then `supplied through lineI1 and the mass agitated until a smooth homogeneous composition isobtained.

When the mass in the kettle has become smooth is usually operatedcountercurrently to the direc-f tion of the flowfof the grease from lineI8 and countercurrently to the direction of the cool- The scraper screwis operated by the motor 25 through' gears 26 and transmission 21. Thecooled grease -Vpasses from the chiller through line 28.

In batch operation the cooled grease is recycled through line 28 to thekettle III. By such recycling the entire quantity grease composition isbrought to about the transition temperature at Vfree owing slurrycomposition.

about the same time. When this temperature within the mass is reached,agitation within the kettle is discontinued and the mass is allowed tosettle and to cool further until the transition in structure has beensatisfactorily effected. The gel composition is then removed from thekettle through a T 29 on linei9 and passed to shipping containers,

In continuous operation it is'usual to employ a series of kettlessimilarly equipped to that designated by the numeral I and to pass thehot mixture to the chiller in a relatively continuous stream from thevarious kettles through the T 30 on line I9. In this manner of operationthe cooling effected in the chiller is more complete than that in batchoperation, namely the cooling in the chiller is effected to about thetransition temperature. tion is passed directly through a T 3| on line28 to the shipping containers wherein settling and further cooling toatmospheric temperature are effected.

Figure 2 indicates a second processing method by which the grease can beprepared. According to this process the oil is passed from a supply tank40 through lines 4| and 42 into a countercurrent rapid batch mixer 43.To the mixer 43 is also added through the hopper 44 the required amountsof aluminum soap and phenolic compounds. The oil, the aluminum soaps andthe phenol are added in quantities so as to form a The slurry is thenpassed through line 45 to an orifice mixer 46, to which is also suppliedthrough line 41 the further quantities of oil from the supply 40, toform the grease of the desired composition. The mixture is then passedthrough line 48 and pump 48 to the coil heater 50 wherein it is heatedto the necessary compounding temperature which is usually about 300 F.by means of steam passed through lines 5| and 52. r.ihe hot mixture thenpasses through line 63 to a surge tank 54 wherein any occluded air orgas formed during the heating process is permitted to escape through thevent pipe 55. To-the surge tank mayalso be supplied through line 5B anoil thickening agent, such as polybutene or latex, from the tank 61. Thegrease mixture is removed from the surge tank 54 through the line 53 andpassed to the screw conveyor type chiller 69, which is cooled by thewater Jacket 60. The grease is cooled usually therein to a temperatureofabout 90-100" F. and then passed directly through pipe 6| to theshipping containers 62.

'I'he following example is presented to illustrate the preparation andvarious characteristics of suitable greases 4prepared according to thisinvention:

A grease of the `following composition was prepared:

, I Per cent Aluminum stearate 6. 50 Tert.octy1 phenol 0. 75 Lubricatingoil of 200 S. U. vis/210 F 14. 00 Polybutene 0. Lubricating oil of 70 S.U. via/210 F..-- 78. 50

The lubricating oil of 200 S. U. viS./210 F. 'and the aluminum stearatewere charged to a heating kettle as illustrated in Figure 1, and themixture agitated by means of therpaddles for about 1 5 minutes. Then thelubricating oil of 70 S. U. vis/210 F. preheated to about 130 F. wasadded and agitation continued. The tert.octyl phenol and polybutene werethen "added and the temperature of the mixture raised to about. 280 F.

The cooled grease in such opera- At this point'the heating wasdiscontinued and the mixture cooled by passing cold water through thekettle jacket. The grease was thus cooled with agitation to about 95 F.,then agitation discontinued and the mass allowed to stand for 21/2'hours. The grease after this period ot standing was found to be of a.smooth plastic gel nature.' The grease so prepared had an unworkedpenetration at 90 F. of 255, and a. worked penetration at 90 F. of 338.

Ihis'grease was then heated to 310 F. and held at that temperature forminutes. 'I'he grease'was cooled to 305 F.' by circulating cold waterthrough the kettle jacket and then pumped into the cooler supplied withwater at '12 F. The vgrease after one pass through the cooler(temperature o! exit water 88 F.) was passed into various containers atdifferent temperatures and allowed to cool therein to atmospherictemperature. The following table presents the results:

. Worked penetrations 24 hours Amount and capa- Temperalater' city ofcontainer ture, F

. Outer layers Core l The second value was obtained twelve days laterthan the ilrst 85 value.

Comparison of these data demonstrates that y continued. The gre'ase at300 F. was circulated over a prolonged `period through the cooler intokettle with the following results:

Temperature, F. at end of cooler Temperature Time in keine, F.

2 hours 35 mins 113 130 The grease cooled to 113 F. was then passed atthe rate of 16 lbs/minute .to illl a 400 lb. barrel. After standing for20 hours at atmospheric` conditions the core was found to have atemperature vo! F. and the following penetration data were obtained.

Representative sample Outer on" of same malayers terialoooled in 1 poundcan Unworkcd penetration 261 310 Worked penetration 356 400+ 336Comparison of these data demonstrates the efrect of the rate of coolinginthe presence'o! tert. octy1 phenol of a1uminumstearate greases `thefollowing penetration values:

widely different size containers, and that the" penetration values ofthe outer layers of cooled bulk masses approximate that of the'productcooled in smaller size vessels. When a sample of the grease compositionf Example I was vpassed directly from the kettle at 300 F. to ll a 400lb. drum and the mass allowed to stand for j10 days, the product was asemi-fluid mass wholly unsuitable as a grease-type lubricant. On theother handV when a similar batch of grease was grease product, havingnov grain formation, and

Rim Center nnworked 261 zes WMM* 353 35o Thus, it has been shown thatsatisfactory aiuminum soap greases can be prepared in the presence ofphenolic compounds from blends of theA soaps of the saturated fattyacids containing between `10 and 20 carbon atoms in the molecule, suchas aluminum stearate, in viscous oils by rapidly cooling from thecompounding temperatures to almost normal temperatures. Thisrapidcooling to atmospheric temperatures permits the grease products tobe packaged directly into bulk shippingcontainers. The discovery of thiseiect of phenolic compounds obviates the timeand labor-consuming and thecostly prior art process of preparing aluminum soap greasesby'pan-cooling and subsequent reworking, and also avoids `theconsistency loss based uponfthe quantity oi' aluminum soap employed. Itwould seem that the action of thephenolic compounds has basis inpreventing the recrystallization of the aluminum soaps at temperaturesbelow about 140 F., that is, an effect in grease compositions similar tothat of pour depressants in waxy mineral oils inhibiting thecrystallization of the wax content. Thus, the use of phenolic compoundspermits departure from the prior art procedure of being able to cool thegrease to minimum temperatures of about 140 F. and then having tocontinue the `preparation oi the grease by pan-cooling, by allowing thehot grease mixture to be cooled with agitation to temperatures wellbelow 140 F. 1n thisvmanner greases having a worked penetration at 77 F.of between about'50 and about 360 or higher may be easily and readilyprepared.

The advantages of the use oi phenolic com--l pounds in the preparationof aluminum soap greases are attained without loss of any of thedesirable properties of aluminum soap-mineral oil grease composites.grease products containing the phenolic comthe various constituentsinsuring good lubricatis exerted lan added stabilizing effect. In otherwords. it appears that a minor portion of the l composition exists as acolloidal dispersion of the soap compounds in a relatively stableemulsion of a major portion of a colloidal dispersion of other soapcompounds in the mineral oil of suitable consistency. This relationship,as indicated by tests, such as penetration, adhesiveness ,tov metalsurfaces, internal cohesion, melting point, etc., .is consideredimportant in order that there be formed on the bearing surfaces asatisfactory adhesive lubricating iilm while the colloidal phasefunctions to offer substantial resist- It would seem that in the' cooledin the kettle to 95 F. and then passed into Va 400 lb. drum, the productwas a satisfactory ance toward heat conduction from the surface filminto the mass thereby minimizing the eflect v of friction, speedand'load during service upon the bulk of the grease composition.

. The present invention is not to be limited by any theory ofmanufacture or to any particular` type of aluminum soaps, but only tothev follow ing claims or their equivalent.

What is claimedis: v

1. Process for preparing##aluminum l soap greases which comprisesthoroughly mixing at a temperature from about 280 F. up to about 300" F.a viscous mineral lubricating oil,`abo utf3 to of aluminum stearate andfrom aboutv 15.40.2595, to 1.5%,of a phenolic compound,VV rapidlygreases which comprises thoroughly mixing at a cooling the heatedmixture to a temperature be-V low 140 F. and allowing the mass to stand.Y I

2. Process according to claim 1 in which the phenolic compound is amono-nuclear phenol.

phenolic compound is an alkyl phenol having between 3 and 8 carbon atomsin the alkyl grouping.

4. Process according to claim 1 in which the phenolic compound istert.octyl phenol.

thorough mixing at an elevated temperature is veffected by passing theingredients rst through an orifice mixer and then through a coil heater.6. Process for preparing aluminum soap temperature from about 280 F. upto about 300 F. a viscous mineral lubricating oil, about 3 to 10% ofaluminum stearate and from 0.25% to f 1.5% of amano-nuclear phenoliccompound, rap- 36 idly cooling the heated mixture to a temperature belowabout 140 F., in a owing stream and allowing the cooled mass tostand. Y

y ,7. Process for preparing aluminum soap grease according to claim 6Vin which the rapid 40 cooling'is eiected-by passing through a helicalscrew scraper type cooling equipment in which the flow of the heatedmixture is in the opposite direction to that of the motion of the screwand countercurrent to the ow of cooling Jacket.

8. Process according to claim 6 in which the mono-nuclear phenoliccompound is an alkylated mono-nuclear phenol. 0

9. Process for preparingsemi-Huid aluminum soap greases for thelubrication of chassis parts of crawler-type tractors which comprisesthoroughly mixing at a temperature from about 280 F. up to about 300 F.a viscous mineral lubricat-V ing'oil of betw( en 150-200 seconds Sayboltat 210 F., about i, to 10% of aluminum stearate pounds, the advantageousrelationship between 60 ing fquality is attained and that in additionthere and from 0.25% to 1.5% of an' alkylated mononuclear phenoliccompound, rapidly cooling theheated mixture in a iiowing stream to atemperature below about F., and then allowing the mixture to stand.

10. A lubricating grease for the chassis parts of crawler-typetractors-comprising a ,mineralV lubricating oil having `a viscosity offrom about to 200 seconds Saybolt at 210 F., about 5% aluminum stearate,0.75% of an alkylated'mononuclear phenol, about 0.1% polybutene, thewhole being worked intoa homogeneous mass laizag/ing a worked:penetration at 77 F. oi' about 11. A lubricatingl grease according toclaim'lO in which the alkylatedmono-nuclear phenol is tert.octyl phenol.Y

12. Process forl preparing an aluminumv soap 75 grease which comprisesthoroughly mixing at an 3. Process according to claim 1 in which the" 5.Process according to claimv 1 in which the.

the fluid m the oezaturc sufcent to eect substantr lof; blending aviscous mineral lubricating oil with at least 3% of an aluminum soap ofa saturated fatty acid containing at least 13. Process according toclaim 12 ln which the pheaolo compound ls an alkyl phenol ha from 3 to 8carbon atoms in the alkyl grouping.

l. Process according to claim 12 in which'the carbon atoms per moleculeand from about 5 phenolic compound is tem-octyl phenol.

to 3.5% of phenolic compound, and rapidly cooling the entire mass inbulk without agitation to a temperature below wir F.

LORNE W. SPR' l JOM C. ZIIMDIIER.

